A sexual position in which the girl is seated in front of the guy, with her back to him (preferably at a slightly higher height). Her legs are spread up and out to the side in a "V". With his right hand, he tickles the clit and with his left hand, he plays with the ever-important left boob (which is clearly the better of the boobs). The action thus mimmicks the way in which one would play a cello.

Stosh: I heard RyHakins was playing the cello on Catherine last week.
Zack: Really? Where'd he learn to do that?
Stosh: From Rob Becker I'd imagine.